Note from the Editor:

This article, Part 1 of which appears today, was originally published in Marine Fish Monthly some years ago. It is published again here with permission from the author. While some of it may feel dated, the article is as interesting now as it was then. The photos herein are also courtesy of the author and published here with his permission.


When I see coral reefs on television, I notice that there is an altogether different look than I have typically seen in a closed aquarium system. In tanks, there are the soft and stony corals, anemones and the like, that you can buy at your local marine shop, but there is a lot missing. The reef tanks that I have seen were well stocked with healthy plants and animals but the tanks looked sterile with tens or hundreds of species, not thousands.

I see Dendronephthya (carnations or cauliflowers), sponges, and gorgonians for sale but very few seemed to thrive in well-established tanks. Even in magazines, tanks look like beautiful gardens, but they often don't look like the living inshore reefs that I have viewed.

In the reef there is competition for space on the rock, not just competition for space under the light. There is often a myriad of species in any given square foot. In many ocean reefs, the rock is barely visible. This is due to the great crowding of diverse organisms, like boring and encrusting sponges, tunicates and many other corals as they grow over, under and through each other. This happens regardless of lighting. The variety of color and patterns are breathtaking. Vibrant color is one of the things for which reefs are most famous.

I have often wished that I could simply get a football sized chunk of some of the choice live rock that I have seen in pictures. Despite the damage to the environment that would be caused, it wouldn’t do any good because most of the life on this rock would die off, even if it was shipped with the best of care. The right kinds of foods are a strong limiting factor. Many of these corals feed from what is drifting in the water column. We used to call them filter feeders. Now some of these beauties are referred to as Azooxanthelle, Predatory or Non-Photosynthetic Corals (NPS).

The reef tanks that I have run across with softies have more tans, browns, and fluorescent greens than I see in the wild. Most marine tank invertebrates seem to require strong, high quality lighting. The zooxanthellae algae in the flesh of these invertebrates tend to make them different shades of brown and green.

Clams can be expensive exceptions and are often a "must-have" item to add a little color to the tank. Some beautifully colored SPS corals are being successfully raised but not everyone can keep them. Fluorescing corals that look best under deep-blue lighting are getting more popular but aren’t as brilliant under normal illumination. Many thriving marine tank inhabitants, outside of the NPS group, can flourish with little or no feeding at all.

My old experimental filter feeder tank in 2000.

Many filter feeders come in brilliant reds, yellows, oranges, purples, blues and greens. They are often fairly fast growing too. They can pop up in crevices and start to grow over rocks and other filter feeders, packing the rock with life. We probably all like to see the enthusiasm of a guest in the home who has a fixated stare at an Elegance Coral or a Rose Tipped Montipora. A greater variety of species can maintain a higher level of interest for the owner of the tank well after the blush of the newest addition to the tank wears off.

Sponges, for example, come in so many different colors, textures, shapes and sizes that they alone could make a tank look beautiful. At a conference that I went to recently, some show tanks were decorated with large sponges that were brilliant in color. None of them were encrusting however, and although they would grow relatively quickly at first, sadly, I knew that a large portion of those specimens would be dead within a year. Improper collection is not always their greatest peril, rather it is starvation.

Many of us have tried to supply filter feeders with ground up shrimp, fish and other foods. We then find that excessive feeding causes other problems in a closed system. Hair algae and slime can quickly become a problem that a few crabs and snails can't handle. After all, how much ground shrimp is there in the open reef?

In the early 90’s, I searched for ways to have my systems handle more feeding. I tried many products but they were all designed for very limited use. Then I got interested in living plankton, thinking that live food would not foul the water. In the night films of reefs there were always clouds of plankton and other debris. I didn’t see any of that in my tank.

I read a lot of material and then bought the setup for growing green water and rotifers, but I didn’t have a lot of luck. I also started a brine shrimp tank that worked.

One problem with the zooplankton that I could raise was that it was primarily on the large end of the spectrum. In addition, zooplankton that was not killed by standard pumps and skimmers was eaten by the fish in no time when the lights were on. In any case, these animals were too large for many of my filter feeders.

Live plankton can often improve water quality rather than degrade it. Phytoplankton cultures were great but were hard for me to maintain without crashes.

There were a few articles on Leng Sy’s system that typically had more plankton than in standard tanks of the day. He used caulerpa to export nutrients instead of using a protein skimmer. He was breaking new ground and was having success. Regrettably, I didn’t find enough literature about it at that time, to feel comfortable with it.

About the same time, I bought and read a copy of Dr. Adey's book Dynamic Aquaria. I was quite impressed by his natural approach that fostered more diversity, particularly as it relates to plankton growth. He designed algae scrubbers to do his nutrient export, and they sounded like they would work, so I built a few dump-bucket-style scrubbers. I used them on my oldest tank before settling on a final design. This type of algae-based system can keep liquefied and powdered foods suspended longer because only the byproducts of decayed food are treated as fertilizer and removed by the algae as it passes through the strands.

The version that I used on the filter feeder tank was four-feet long with a low profile, so it could fit under the tank’s hood. I liked it so much that I still use it today. This dump bucket produces splashes, surge and turbulence, although it was not as strong as I expected.

The use of skimmers is a great idea and most commonly prescribed, but they can remove the food that is needed by these demanding corals. For this reason, many people use a feed cycle to turn them off for a time, during and right after feeding. While this may not have been a good idea for others, I stopped using a skimmer altogether for this long experiment.

Back then, some people were also experimenting with the so called Jaubert live-sand system because it didn’t rely on pumps for mechanical filtration at all.

Adey and Jaubert seem to agree on having an aragonite sand bed but differ on the setup. In both cases calcium carbonate sand beds can lower nitrates and lightly help to regulate pH, calcium levels and other parameters of a healthy system.

I read up on a popularized version of the Jaubert setup and decided to add a plenum under the sand bed as an experiment when I started the investigational 130-gallon tank.

This idea is not as popular as it was then because there are so many other good choices but I had good results with it at the time.


While researching different sand beds, someone told me to call Richard Greenfield because he knew a lot about both sand and filter feeders. He was trained as a marine geologist before becoming an owner of Caribsea™.

He schooled me on the reasons for different grain sizes and why using only one size, in a given place is important. I eventually purchased my sand and crushed coral from him.

I ran this experimental tank for about 10 years or so before shutting it down because I relocated to a new state.

My trial showed that the tank will run okay with just the plenum sand bed alone, and I did get good skeletal growth without the addition of Kalkwasser. My clam grew from five to nine inches in eighteen months. However, I chronically overfed, so I needed more horse power to make the tank run cleaner, and thus I ended up using the static sand bed only as a supplemental system for my tank.

After the first three months of operation using the sand bed alone, I started using my final scrubber design and began to harvest the algae. I also put a small bag of carbon in the scrubber to remove dissolved organic compounds but I didn’t force water through the bag. This would act as a mechanical filter or food trap. The inhabitants in my tank perked up and the live rock stayed cleaner. The hair algae dyed off or was eaten by my three snails and didn't grow back. The tank got so stable that it seemed almost bullet proof. Eventually, even the snails were starved out.

While talking to Mr. Greenfield about flow and turbulence in a reef tank, he told me that he was playing around with a new pump design, just for personal use. He suggested that I experiment with a pair so I did. They created more turbulence than flow. Although I had a fair amount of flow from power heads, I put his pumps in my tank and had some interesting results.

Some sponges and feather dusters seemed to need the better water flow and turbulence than I thought. They seem to do best where they, at first, looked like they were getting a beating. They quickly recovered and then thrived.

Often long-tentacle corals are incompatible with this turbulence but placing them farther away from the source would allow them to adjust after a few days.

Small polyp stony corals have long been reported to do well in strong current. Some people report that rather intense turbulence allows these corals to diffuse carbon dioxide and other metabolic wastes from their tissues. This seems to return much of the lighter colors that they had in the wild. My starter SPS corals seemed to like the strong turbulence that the pumps provided, so I also put them near one of the pumps and almost right under the splash of the dump bucket.

As a recent side note, the spider sponge that I bought last year started its predicted decline so I put it in very strong water flow. I found that it didn’t snap in half because it was quite elastic and bent way over, like a fishing pole, at the peak of the 30 second cycles that I use. Within hours, it started to show its polyps again and in a few days it looked fully recovered.

Mr. Greenfield also told me to call Marc Weiss because he had an office tank where sponges and assorted filter feeders were thriving. I did call him and it turned out that he was quite a pioneer. To start with, he gave me two products to try but would not tell me what they would do for my tank. He didn’t want to influence my observations.

One product was a liquid and was later released as Coral Vital™. After using it, I noticed that the tank looked cleaner and I could feed the tank more. In addition, the growth of coralline algae accelerated. Unfortunately, fresh batches of this product are not offered for sale right now.

Today, there are several products that directly provide or stimulate the growth of bacteria. You have to be careful with some of them but back then, we didn’t have any experience to draw from.

I tried using brewer’s yeast as a food source, but it produced green and red slime within a week, so I stopped using it completely. Ground shrimp and fish did about the same thing, so I used it sparingly.

I also tried acidophilus as a bacteria source but I did not find out how high dosages would affect my tank. Spirulina is another food source that I deployed. I used about a half of capsule per day.

The other product that Marc Weiss sent me was later called Spectra Vital™. It was a reddish brown powder that stayed suspended in the water column for a long time because it was so fine in texture. I only used about a heaping teaspoon per day because a little goes a long way. This was enough to completely cloud the tank for hours. I fed at night so that it would clear up by the time I turned on the lights the next day. I have a bag of it now but when it runs out, I will have to find a replacement for it as well.

I didn’t have scavengers except for worms so it appeared that virtually none of this product ended up in or under the sand bed. I also had a 55-gallon brine shrimp tank. There was almost no current because it just had an air stone in it. If I badly overfed this tank the powder settled out in a few days but did not foul. The brine shrimp simply fed right off of the bottom.

These products, together, seem to provide a wider spectrum of choices to the differing species that require specific size ranges of foods.

After using these products for a month or so, I started to see quite a few small white or purple feather dusters growing near the two turbulence pumps. I had seen them around my tanks for years but they were few in number and small in size.

I also saw what I thought was a yellow slime growing on two of my rocks. I never saw yellow slime in my tank before and it was localized so I waited to see what would develop. It turned out to be the beginnings of yellow sponges. It was not like my "liver sponges" that start out orange-yellow in the shade but turn gray in the bright light. This was a bright yellow, frilly, encrusting sponge that I had not seen before. It completely covered two fist-sized rocks. I also got one of my Clathrina clathrus sponges that normally grow to only a quarter inch in diameter in my tank, to grow to two inches in size in four months. This sponge was also showing up in white in addition to the typical yellow.

After six months of the new turbulence and feeding regime, the feather dusters completely covered several rocks. I estimate over 1000 individuals. Some feather dusters have grown to about an inch and a half in diameter! New sponge was covering some of the feather worm casings while leaving the feather heads exposed. I also began to see small red and orange boring sponges on a few rocks as well as a small ball or moon sponge. There was a species of purple sponge that was growing as well.

I discontinued the use of the powder to see if the growth was a coincidence. The bigger feather dusters stayed retracted most of the time, and my encrusting sponges all but died out. I then restarted the use of the reddish powder. The feather dusters responded right away and the sponges slowly began to grow back.
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This is the end of Part 1. Part 2 will appear tomorrow.


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Author Profile: @herring_fish

Asa Herring has been a marine aquarist for many years. He has written many articles for glossy aquatic magazines, and he is kindly allowing Reef2Reef to publish some of his articles again here.